Many sites got penalized during the last few years but at least the people from Google think about the community and share tips and advices on how to improve your site’s appearance.
For example, let’s go back in time to 2012 when Google released their DMCA algorithm penalty. This algorithm got updated only once, and had the purpose of downgrading the ranking of a website which received a specific amount of DMCA complaints.
The new related information came from Eric Kuan who, as a Google spam fighter, gave valuable advice on algorithm penalties. This happened in a Google Webmaster Help forum and Eric said that:
If you’ve made significant changes to your site, note that bigger changes can take time to settle down. Also, keep in mind that a lot of things can change over the years and your site’s rankings and performance metrics can change over the years.
He added that if you are suspecting your site to be affected by a specific algorithm, do not give up and make time for rooting and eventually removing these sites. Eric says that in this case separating the main domain from any user generated content on your site will also help you because, in the end, you cannot control what some users will put on their websites.